/* === Problem / Task Page · Light Theme === */

.problem-header {
  background: #f7f7f8;
  border: 1px solid #ebebeb;
  color: #0d0d0d;
  padding: clamp(2rem, 4vw, 3rem) 0;
  margin-bottom: clamp(1.5rem, 3vw, 2rem);
  text-align: center;
  border-radius: 12px;
}

.problem-header h1 {
  font-size: clamp(1.4rem, 2.8vw, 1.9rem);
  margin-bottom: 0.5rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: #0d0d0d;
}

.problem-header .meta {
  display: flex;
  justify-content: center;
  gap: clamp(0.75rem, 1.5vw, 1.5rem);
  margin-top: 0.75rem;
  flex-wrap: wrap;
}

.problem-header .meta-item {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0.35rem 0.75rem;
  background: #ffffff;
  border: 1px solid #e5e5e5;
  border-radius: 6px;
}

.problem-header .meta-item span {
  color: #6e6e80;
  font-size: 0.88em;
}

.problem-intro {
  background: #ffffff;
  border: 1px solid #ebebeb;
  border-radius: 12px;
  padding: clamp(1.25rem, 2.5vw, 2rem);
  margin-bottom: clamp(1.25rem, 2.5vw, 2rem);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.04);
}

.problem-intro h2 {
  color: #0d0d0d;
  margin-bottom: 0.5rem;
  font-size: clamp(1.1rem, 2vw, 1.3rem);
  font-weight: 600;
  letter-spacing: -0.01em;
}

.problem-intro .description {
  font-size: 0.93em;
  line-height: 1.7;
  color: #6e6e80;
  margin-bottom: 1rem;
}

.problem-intro .details {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 0.75rem;
  margin-top: 1rem;
}

.problem-intro .detail-item {
  padding: 0.85rem;
  background: #f9f9fb;
  border-radius: 8px;
  border: 1px solid #ebebeb;
}

.problem-intro .detail-item strong {
  display: block;
  color: #999;
  margin-bottom: 0.3rem;
  font-size: 0.78em;
  letter-spacing: 0.03em;
  text-transform: uppercase;
  font-weight: 500;
}

.problem-intro .detail-item span {
  color: #0d0d0d;
  font-size: 0.93em;
  font-weight: 500;
}

.tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem;
  margin-top: 0.75rem;
}

.tag {
  display: inline-block;
  padding: 0.2rem 0.55rem;
  background: #f7f7f8;
  color: #6e6e80;
  border: 1px solid #e5e5e5;
  border-radius: 6px;
  font-size: 0.82em;
  font-weight: 500;
}

.problem-leaderboard {
  background: #ffffff;
  border: 1px solid #ebebeb;
  border-radius: 12px;
  padding: clamp(1.25rem, 2.5vw, 2rem);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.04);
}

.problem-leaderboard h2 {
  color: #0d0d0d;
  margin-bottom: 1rem;
  font-size: clamp(1.1rem, 2vw, 1.3rem);
  font-weight: 600;
  letter-spacing: -0.01em;
}

.problem-nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin: clamp(1rem, 2vw, 1.5rem) 0;
  padding: 0.85rem 1rem;
  background: #f9f9fb;
  border: 1px solid #ebebeb;
  border-radius: 10px;
}

.problem-nav a {
  color: #6e6e80;
  text-decoration: none;
  font-weight: 500;
  padding: 0.35rem 0.65rem;
  border-radius: 6px;
  transition: color 0.15s ease, background 0.15s ease;
  font-size: 0.9em;
}

.problem-nav a:hover {
  color: #0d0d0d;
  background: #efefef;
}

.problem-nav .current {
  color: #999;
  font-weight: 500;
  font-size: 0.88em;
}

.back-link {
  display: inline-block;
  margin-bottom: 1rem;
  color: #6e6e80;
  text-decoration: none;
  font-weight: 500;
  padding: 0.35rem 0.6rem;
  border-radius: 6px;
  transition: color 0.15s ease, background 0.15s ease;
  font-size: 0.9em;
}

.back-link:hover {
  color: #0d0d0d;
  background: #f7f7f8;
}

.back-link::before {
  content: '← ';
  margin-right: 0.25rem;
}

@media (max-width: 768px) {
  .problem-header .meta {
    flex-direction: column;
    gap: 0.5rem;
  }

  .problem-intro .details {
    grid-template-columns: 1fr;
  }

  .problem-nav {
    flex-direction: column;
    gap: 0.5rem;
    text-align: center;
  }
}